“…273,283 Various exogenous probes with high contrast have also been extensively developed, including inorganic and organic dyes, 274 magneto-optical and photochromic probes, 283 nanoparticles, 282,287 and genetically encoded probes, 281 to achieve improved resolution and sensitivity while providing multi-parametric photoacoustic imaging. 283 This imaging modality has proven its clinical and preclinical value in functional, structural, and molecular aspects of diseases and has been used for physiologically and pathologically imaging various organs and tissues, including breast cancer, [288][289][290][291][292] neural tissues, 277,287,[293][294][295] fingers, 296 sentinel lymph nodes, 277,292,297 the cardiovascular system, [298][299][300][301][302] the prostate, 303,304 skin, 305 cancer therapy, 273,274,306 muscle oxygenation, 307 metabolic status, 274,283 eyes, 308,309 plaque pathophysiology, 310 tumor microenvironment (pH, enzymes, radical oxidation species (ROS), and metal ions, among others), 274 and biomaterial-tissue interactions to assess the functions of the engineered tissue/organ constructs. <...>…”